Variable-depth seismic source and method

Abstract

Method and marine acoustic source array for generating an acoustic wave in a body of water. The marine acoustic source array includes at least one sub-array. The at least one sub-array includes a float from which plural source points are attached. The source points may be provided on a curved line, straight line, or other desired shape so that a variable-depth source is obtained with a single float. The source points may be divided into groups and the groups may be provided on the curved line, straight line or other desired shape.

What is claimed is: 
     
       1. A marine acoustic source array for generating an acoustic wave in a body of water, the marine acoustic source array comprising:
 a first sub-array configured to be towed by a vessel, the first sub-array including a first float and plural first source points connected to the first float, 
 wherein the plural first source points are divided into at least three groups (G1 to G3), each group is provided at corresponding distinct first depths (D1 to D3), includes plural source points and is attached to a corresponding region of the first float, and any two groups do not share a same corresponding region of the first float, 
 wherein the first depths form an imaginary first curved line. 
 
     
     
       2. The source array of  claim 1 , further comprising:
 a second sub-array configured to be towed by the vessel and having plural second source points, wherein the plural second source points are divided into at least three groups (G4 to G6) and each group is provided at corresponding second depths. 
 
     
     
       3. The source array of  claim 2 , wherein the first depths are different from the second depths. 
     
     
       4. The source array of  claim 2 , wherein the first depths overlap with the second depths. 
     
     
       5. The source array of  claim 1 , wherein the first depths increase from a head of the first float toward a tail of the first float. 
     
     
       6. The source array of  claim 1 , wherein plural second source points that form a second sub-array are divided into at least three groups (G4 to G6) and each group is provided at corresponding second depths, and the second depths form an imaginary straight line. 
     
     
       7. The source array of  claim 1 , wherein plural second source points that form a second sub-array are divided into at least three groups (G4 to G6) and each group is provided at corresponding second depths and the second depths form an imaginary second curved line. 
     
     
       8. The source array of  claim 7 , wherein the second curved line is identical to the first curved line so that the source array has the plural first and second source points distributed on a cylindrical surface. 
     
     
       9. The source array of  claim 7 , wherein the first and second curved lines are parts of a circle but have different radiuses so that the source array has the plural first and second source points distributed on a spherical surface. 
     
     
       10. The source array of  claim 1 , wherein the plural second source points that form a second sub-array are divided into at least three groups (G4 to G6) and each group is provided at corresponding second depths and the second depths form an imaginary straight line. 
     
     
       11. The source array of  claim 1 , wherein a ratio of (i) a shortest depth of the first depths and (ii) a longest depth of the first depths is about 2.5. 
     
     
       12. A marine acoustic source array for generating an acoustic wave in a body of water, the marine acoustic source array comprising:
 a first sub-array configured to be towed by a vessel, the first sub-array including a first float and plural first source points connected to the first float, 
 wherein each of the plural first source points is provided at a corresponding first depth, each first depth being different from other first depths, the first depths forming a first curved line. 
 
     
     
       13. The source array of  claim 12 , further comprising:
 a second sub-array having plural second source points, wherein the plural second source points are provided at corresponding second depths, each second depth being different from other second depths. 
 
     
     
       14. The source array of  claim 12 , wherein plural second source points that form a second sub-array are provided at corresponding second depths, each second depth being different from other second depths, and the second depths form a second curved line. 
     
     
       15. The source array of  claim 12 , wherein plural second source points that form a second sub-array are provided at corresponding second depths, each second depth being different from other second depths, and the second depths form a straight line. 
     
     
       16. The source array of  claim 12 ,
 wherein plural second source points that form a second sub-array are provided at corresponding second depths, each second depth being different from other second depths, and the second depths form a second curved line, and 
 wherein the second curved line is identical to the first curved line so that the source array has the plural first and second source points distributed on a cylindrical surface. 
 
     
     
       17. A method for generating an acoustic wave underwater, the method comprising:
 towing underwater a marine acoustic source array that includes a first sub-array; 
 connecting plural first source points to a first float of the first sub-array; and 
 generating the acoustic wave with the plural first source points, wherein each of the plural first source points is provided at a corresponding first depth, each first depth being different from other first depths, the first depths forming a first curved line.